编程思维案例 - 案例 - Java - 计算机与科学

# 买飞机票

需求：用户购买机票时，机票原价会按照淡季、旺季，头等舱还是经济舱的情况进行相应的优惠，优惠方案如下：5-10 月为旺季，头等舱 9 折，经济舱 8.5 折；11 月到来年 4 月为淡季，头等舱 7 折，经济舱 6.5 折，请开发程序计算出用户当前机票的优惠价

	public class Demo1 {
	public static void main(String[] args) {
	double price = planePrice(1000, 8, "经济舱");
	System.out.println("优惠价是" + price);
	}

	// 买飞机票
	public static double planePrice(double price, int month, String type) {
	if (month >= 5 && month <= 10) {
	switch (type) {
	case "头等舱":
	price *= 0.9;
	break;
	case "经济舱":
	price *= 0.85;
	break;
	}
	} else {
	switch (type) {
	case "头等舱":
	price *= 0.7;
	break;
	case "经济舱":
	price *= 0.65;
	break;
	}
	}
	return price;
	}
	}

# 开发验证码

需求：开发一个程序，可以生成指定位数的验证码，每位可以是数字、大小写字母

	import java.util.Random;

	public class Demo2 {
	public static void main(String[] args) {
	System.out.println(createCode(4));
	}

	// 开发验证码
	public static String createCode(int num) {
	Random r = new Random();
	String code = "";
	for (int i = 0; i < num; i++) {
	int type = r.nextInt(3);
	switch (type) {
	case 0:
	// 随机数字
	code += r.nextInt(10);
	break;
	case 1:
	// 随机大写字母：A (65) Z (65+25)
	//alt + 回车键：转换
	char ch1 = (char) (r.nextInt(26) + 65);
	code += ch1;
	break;
	case 2:
	// 随机小写字母：a (97) z (65+25)
	char ch2 = (char) (r.nextInt(26) + 97);
	code += ch2;
	break;
	}
	}
	return code;
	}
	}

# 评委打分

需求：在唱歌比赛中，可能有多名评委要给选手打分，分数是 [0 - 100] 之间的整数。选手最后得分为：去掉最高分、最低分后剩余分数的平均分，请编写程序能够录入多名评委的分数，并算出选手的最终得分

	import java.util.Scanner;

	public class Demo3 {
	public static void main(String[] args) {
	System.out.println("当前选手的得分是：" + getAverageCode(6));
	}

	// 评委打分
	public static double getAverageCode(int number) {
	int[] scores = new int[number];
	Scanner sc = new Scanner(System.in);
	for (int i = 0; i < scores.length; i++) {
	System.out.println("请输入第" + (i + 1) + "个评委的分数：");
	int score = sc.nextInt();
	scores[i] = score;
	}

	int sum = 0;
	int max = scores[0];
	int min = scores[0];
	for (int i = 0; i < scores.length; i++) {
	int score = scores[i];
	sum += score;

	if (score > max) {
	max = score;
	}
	if (score < min) {
	min = score;
	}
	}
	return 1.0 * (sum - max - min) / (number - 2);
	}
	}

# 数字加密

需求：某系统的数字密码是一个四位数，如 1983，为了安全，需要加密后再传输，加密规则是：对密码中的每位数，都加 5，再对 10 求余，最后将所有数字顺序反转，得到一串加密后的新数

	public class Demo4 {
	public static void main(String[] args) {
	System.out.println("加密后的数字为：" + encrypt(1983));
	}

	// 数字加密
	public static String encrypt(int number) {
	int[] numbers = split(number);

	for (int i = 0; i < numbers.length; i++) {
	numbers[i] = (numbers[i] + 5) % 10;
	}
	reverse(numbers);

	String data = "";
	for (int i = 0; i < numbers.length; i++) {
	data += numbers[i];
	}
	return data;
	}

	public static int[] split(int number) {
	int[] numbers = new int[4];
	numbers[0] = number / 1000;
	numbers[1] = (number / 100) % 10;
	numbers[2] = (number / 10) % 10;
	numbers[3] = number % 10;
	return numbers;
	}

	public static void reverse(int[] numbers) {
	for (int i = 0, j = numbers.length - 1; i < j; i++, j--) {
	int temp = numbers[j];
	numbers[j] = numbers[i];
	numbers[i] = temp;
	}
	}
	}

# 数组拷贝

需求：请把一个整型数组，例如存了数据：11，22，33，拷贝成一个一模一样的新数组出来

	public class Demo5 {
	public static void main(String[] args) {
	int[] arr = {11, 22, 33, 44};
	int[] newArr = copy(arr);
	printArray(newArr);
	}

	// 数组拷贝
	public static int[] copy(int[] arr) {
	int[] newArr = new int[arr.length];
	for (int i = 0; i < arr.length; i++) {
	newArr[i] = arr[i];
	}
	return newArr;
	}

	// 打印数组
	public static void printArray(int[] arr) {
	System.out.print("[");
	for (int i = 0; i < arr.length; i++) {
	System.out.print(i == arr.length - 1 ? arr[i] + "]" : arr[i] + ",");
	}
	}
	}

# 抢红包

需求：一个大 V 直播时发起了抢红包活动，分别有：9、666、188、520、99999 五个红包。请模拟粉丝来抽奖，按照先来先得，随机抽取，抽完即止，注意：一个红包只能被抽一次，先抽或后抽哪一个红包是随机的

	import java.util.Random;
	import java.util.Scanner;

	public class Demo6 {
	public static void main(String[] args) {
	int[] moneys = {11, 88, 666, 999, 9999};
	start(moneys);
	}

	// 抢红包
	public static void start(int[] moneys) {
	Scanner sc = new Scanner(System.in);
	Random r = new Random();
	for (int i = 1; i <= 5; i++) {
	System.out.println("请输入任意内容进行抽奖：");
	sc.next();

	while (true) {
	int index = r.nextInt(moneys.length);
	int money = moneys[index];
	if (money != 0) {
	System.out.println("恭喜你，抽中了" + money + "元");
	moneys[index] = 0;
	break;
	}
	}
	}
	System.out.println("活动结束~~~");
	}
	}

# 找素数

需求：找出 101-200 的素数，并打印出素数的个数

除了 1 和它本身以外，不能被其他正整数整除，就叫素数

	public class Demo7 {
	public static void main(String[] args) {
	// 方法一
	search(101, 200);
	// 方法二
	search2(101, 200);
	// 方法三
	for (int i = 101; i <= 200; i++) {
	if (check(i)) {
	System.out.println(i);
	}
	}
	}

	// 找素数
	public static void search(int start, int end) {
	int count = 0;
	for (int i = start; i <= end; i++) {
	boolean flag = true;
	for (int j = 2; j <= i / 2; j++) {
	if (i % j == 0) {
	flag = false;
	break;
	}
	}
	if (flag) {
	count++;
	System.out.println(i);
	}
	}
	System.out.println("当前素数的个数是：" + count);
	}

	public static void search2(int start, int end) {
	int count = 0;

	OUT:
	// 为外部循环指定标签
	for (int i = start; i <= end; i++) {
	for (int j = 2; j <= i / 2; j++) {
	if (i % j == 0) {
	continue OUT;
	}
	}
	count++;
	System.out.println(i);
	}
	System.out.println("当前素数的个数是：" + count);
	}

	public static boolean check(int data) {
	for (int i = 2; i < data / 2; i++) {
	if (data % i == 0) {
	return false;
	}
	}
	return true;
	}
	}

# 打印乘法表

	public class Demo8 {
	public static void main(String[] args) {
	for (int i = 1; i <= 9; i++) {
	for (int j = 1; j <= i; j++) {
	System.out.print(j + "x" + i + "=" + (j * i) + "\t");
	}
	System.out.println(); // 换行
	}
	}
	}

# 打印三角形

	public class Demo9 {
	public static void main(String[] args) {
	int n = 4;
	for (int i = 1; i <= n; i++) {
	for (int j = 1; j <= (n - i); j++) {
	System.out.print(" ");
	}
	for (int j = 1; j <= (2 * i - 1); j++) {
	// System.out.print("*");
	System.out.print(j % 2 == 0 ? " " : "*");
	}
	System.out.println();
	}
	}
	}

# 模拟双色球

需求：

	import java.util.Random;
	import java.util.Scanner;

	public class Demo10 {
	public static void main(String[] args) {
	int[] userNumbers = userSelectNumbers();
	System.out.println("用户号码为：");
	printArray(userNumbers);

	int[] luckNumbers = createLuckNumbers();
	System.out.println("幸运号码为：");
	printArray(luckNumbers);

	judge(userNumbers, luckNumbers);
	}

	public static int[] userSelectNumbers() {
	int[] numbers = new int[7];
	Scanner sc = new Scanner(System.in);

	for (int i = 0; i < numbers.length - 1; i++) {
	while (true) {
	System.out.println("请输入第" + (i + 1) + "红球号码（1-33之间，不能重复）：");
	int number = sc.nextInt();
	if (number < 1 \|\| number > 33) {
	System.out.println("输入的号码不在1~33之间，请重新输入！");
	} else {
	if (check(numbers, number)) {
	System.out.println("输入的号码重复，请重新输入！");
	} else {
	numbers[i] = number;
	break;
	}
	}
	}
	}

	while (true) {
	System.out.println("请输入最后1个蓝球号码（1-16）：");
	int number = sc.nextInt();
	if (number < 1 \|\| number > 16) {
	System.out.println("输入的号码不在1~16之间，请重新输入！");
	} else {
	numbers[6] = number;
	break;
	}
	}
	return numbers;
	}

	public static int[] createLuckNumbers() {
	int[] numbers = new int[7];
	Random r = new Random();
	for (int i = 0; i < numbers.length - 1; i++) {
	while (true) {
	int number = r.nextInt(33) + 1;
	if (!check(numbers, number)) {
	numbers[i] = number;
	break;
	}
	}
	}

	numbers[6] = r.nextInt(16) + 1;

	return numbers;
	}

	public static void judge(int[] userNumbers, int[] luckNumbers) {
	int redCount = 0;
	int blueCount = 0;
	for (int i = 0; i < userNumbers.length - 1; i++) {
	for (int j = 0; j < luckNumbers.length - 1; j++) {
	if (userNumbers[i] == luckNumbers[j]) {
	redCount++;
	break;
	}
	}
	}

	blueCount = userNumbers[6] == luckNumbers[6] ? 1 : 0;

	System.out.println("命中的红球数量是：" + redCount);
	System.out.println("命中的蓝球数量是：" + blueCount);

	if (redCount == 6 && blueCount == 1) {
	System.out.println("恭喜你，中奖1000万~~~");
	} else if (redCount == 6 && blueCount == 0) {
	System.out.println("恭喜你，中奖500万~~~");
	} else if (redCount == 5 && blueCount == 1) {
	System.out.println("恭喜你，中奖3000元~");
	} else if (redCount == 5 && blueCount == 0 \|\| redCount == 4 && blueCount == 1) {
	System.out.println("恭喜你，中奖200元~~~");
	} else if (redCount == 4 && blueCount == 0 \|\| redCount == 3 && blueCount == 1) {
	System.out.println("恭喜你，中奖10元~~~");
	} else if (redCount < 3 && blueCount == 1) {
	System.out.println("恭喜你，中奖5元~~~");
	} else {
	System.out.println("感谢参与~~~");
	}
	}

	public static boolean check(int[] numbers, int number) {
	for (int i = 0; i < numbers.length; i++) {
	if (numbers[i] == 0) {
	break;
	}
	if (numbers[i] == number) {
	return true;
	}
	}
	return false;
	}

	public static void printArray(int[] arr) {
	System.out.print("[");
	for (int i = 0; i < arr.length; i++) {
	System.out.print(i == arr.length - 1 ? arr[i] + "]" : arr[i] + ",");
	}
	System.out.println();
	}
	}

Java